1. Identifying Causal Estimands for Time-Varying Treatments Measured with Time-Varying (Age or Grade-Based) Instruments
- Author
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Steiner, Peter M, Park, Soojin, and Kim, Yongnam
- Subjects
Mathematical Sciences ,Statistics ,Bias ,Humans ,Models ,Statistical ,Students ,Causal inference ,collider bias ,same-age comparison ,same-grade comparison ,time-varying instruments ,time-varying treatments ,Commerce ,Management ,Tourism and Services ,Psychology and Cognitive Sciences ,Social Sciences Methods ,Commerce ,management ,tourism and services ,Mathematical sciences ,Psychology - Abstract
This commentary discusses causal estimands of same-age and same-grade comparisons for assessing grade-retention effects on student ability and performance. Using potential outcomes notation, we show that same-age and same-grade comparisons refer to different retention-promotion contrasts and therefore assess different causal questions. We also comment on deleting versus censoring records of students who dropped out of the study or do not belong to the treatment regimes under investigation. Whereas deleting entire student records potentially induces collider bias, censoring circumvents bias if censoring is ignorable given the observed pretreatment covariates.
- Published
- 2016